If the INMB can be drawn from de, dc and lambda with create_object_inmb, one can also make directly an hypothesis on the value of the INMB.
: INMB expected Incremental Net monetary Benefit.
Returns the Incremental Net Monetary Benefit (inmb)
sets the inmb of this INMB_DIRECT object
create_object_inmb_direct the constructor
create_object_inmb to calculate the INMB